#!/bin/bash

# Munin plugin which reads the hourly, daily and monthly bandwidth usage.
#
# (c) 2011 Bram Schoenmakers <me@bramschoenmakers.nl>

#%# family=contrib
#%# capabilities=autoconf

# par1 message
error() {
  [ $# = 1 ] && echo "$1" >&2
  exit 1
}

# par1: "hourly", "daily" or "monthly"
# par2: "tx" or "rx"
getBandwidth() {
  [ $# != 2 ] && exit 1

  local FIELD=-1
  [ $2 = "rx" ] && FIELD=4
  [ $2 = "tx" ] && FIELD=5

  [ "$FIELD" -eq -1 ] && exit 1

  if [ $1 = "hourly" ]; then
        local DATA=$(echo "$VNSTAT" | grep "^h;$(( 0 + $(date +%k) ))")
        local MIB=0
        FIELD=$(( $FIELD - 2 ))
  else
        local DATA=$(echo "$VNSTAT" | grep "^${1:0:1};0")
        local MIB=$(echo "$DATA" | cut -d ';' -f $FIELD)
  fi
  local KIB=$(echo "$DATA" | cut -d ';' -f $(( $FIELD + 2 )) )

  echo "scale=3; $MIB + ( $KIB / 1024 )" | bc
}

# par1: "hourly", "daily" or "monthly"
# par2: value so far
getEstimate() {
  [ $# != 2 ] && exit 1

  case "$1" in
    "hourly")
      local MINUTESPASSED=$(( $( date +%M ) ))
      local MINUTESTOTAL=60
      ;;
    "daily")
      local MINUTESPASSED=$( echo "$( date +%H ) * 60 + $( date +%M )" | bc )
      local MINUTESTOTAL=1440
      ;;
    "monthly")
      local MINUTESPASSED=$( echo "( $( date +%d ) - 1 ) * 1440 + $( date +%H ) * 60 + $( date +%M )" | bc )
      local DAYSINMONTH=$(date -d "$(date +%Y)-$(($(date +%-m)+1))-01 -1 day" +%d)
      local MINUTESTOTAL=$(( $DAYSINMONTH * 1440 ))
      ;;
  esac
  if [ "x$MINUTESPASSED" = "x0" ]; then
	echo "0.0"
  else
  	echo "scale=1; $MINUTESTOTAL * $2 / $MINUTESPASSED" | bc
  fi
}

PARAMS=${0#*vnstat_}
INTERFACE=$(echo "$PARAMS" | cut -d _ -f 1) # eth0
PERIOD=$(echo "$PARAMS" | cut -d _ -f 2) # hourly, daily, monthly
DIRECTION=$(echo "$PARAMS" | cut -d _ -f 3) # rx or tx

# determine whether estimates should be shown
[ \( "${estimate:-0}" = 1 \) -o \( "${estimate:-0}" = "yes" \) -o \( "${estimate:-0}" = "true" \) ] && ESTIMATE=1 || ESTIMATE=0

# sanity checks
[ "$PERIOD" = "hourly" ] || [ "$PERIOD" = "daily" ] || [ "$PERIOD" = "monthly" ] || error "Invalid period."
[ "$DIRECTION" = "rx" ] || [ "$DIRECTION" = "tx" ] || [ "$DIRECTION" = "total" ] || [ "$DIRECTION" = "rxtx" ] || error "Invalid direction."

case "$1" in
  config)
    echo graph_category network
    echo graph_vlabel MiB

    PERIODSTRING=${PERIOD%ly}
    PERIODSTRING=${PERIODSTRING/dai/day}
    if [ "$DIRECTION" = "rxtx" ]; then
      echo "graph_title Network bandwidth for $INTERFACE ($PERIOD, rx and tx)"
      echo value.label rx
      echo value2.label tx

      # show estimates
      if [ $ESTIMATE -eq 1 ]; then
        echo "estimate.label rx estimate for this $PERIODSTRING"
        echo "estimate2.label tx estimate for this $PERIODSTRING"
      fi
    else
      echo "graph_title Network bandwidth for $INTERFACE ($PERIOD, $DIRECTION)"
      echo value.label $DIRECTION
      [ $ESTIMATE -eq 1 ] && echo "estimate.label estimate for this ${PERIODSTRING}"
    fi

    exit 0;;
  autoconf)
    if ! which vnstat > /dev/null; then
      echo "no (vnstat unavailable)"
    elif ! which bc > /dev/null; then
      echo "no (bc unavailable)"
    else
      echo yes
    fi

    exit 0
    ;;
esac

VNSTAT=$(vnstat -i $INTERFACE --dumpdb)

if [ "$DIRECTION" = "total" ] || [ "$DIRECTION" = "rxtx" ]; then
  VALUE1=$(getBandwidth $PERIOD rx)
  [ $? = 1 ] && error "Could not obtain data."
  VALUE2=$(getBandwidth $PERIOD tx)
  [ $? = 1 ] && error "Could not obtain data."

  [ "$DIRECTION" = "total" ] && VALUE1=$( echo "scale=3; $VALUE1 + $VALUE2" | bc )
else
  VALUE1=$(getBandwidth $PERIOD $DIRECTION)
  [ $? = 1 ] && error "Could not obtain data."
fi

if [ "$DIRECTION" = "rxtx" ]; then
  echo value.value $VALUE1
  echo value2.value $VALUE2

  if [ "$ESTIMATE" -eq 1 ]; then
    echo estimate.value $(getEstimate $PERIOD $VALUE1)
    echo estimate2.value $(getEstimate $PERIOD $VALUE2)
  fi
else
  echo value.value $VALUE1
  [ "$ESTIMATE" -eq 1 ] && echo estimate.value $(getEstimate $PERIOD $VALUE1)
fi